Introduction

The readline functions implement an interface
to the GNU Readline library. These are functions that provide
editable command lines. An example being the way Bash allows you
to use the arrow keys to insert characters or scroll through
command history. Because of the interactive nature of this
library, it will be of little use for writing Web applications,
but may be useful when writing scripts used from a
command line.

As of PHP 7.1.0 this extension is supported on Windows.

Caution

The readline extension is not thread-safe! Thus, the usage of it with any
true thread safe SAPI (like Apache mod_winnt) is strongly discouraged.